Latching apparatus for installing safety valves or the like in wells

ABSTRACT

In accordance with an illustrative embodiment of the invention disclosed herein, an apparatus for releasably latching the lower end of a tubing string in a well casing having a landing nipple therein includes laterally flexible anchors carried by a body structure and held inwardly during running. When the anchors encounter the recesses in the nipple, they resile outwardly to stop downward movement, whereupon a clutch can be released to enable the body structure to be moved downwardly to releasably lock the anchors in set position. A seal on the body structure closes the tubing-to-casing annulus so that it can be used for a pressure path to a remote controlled safety valve installed in the tubing above the latching apparatus. The anchors and body structure are provided with coengageable axial cam surfaces that are automatically engaged by downward movement and releasable by relative rotation so that the latching apparatus can be repeatedly set and released as required during installation of the surface equipment.

United States Patent [191 Majors, Jr. 7

LATCHING APPARATUS FOR INSTALLING SAFETY VALVES OR THE LIKE IN WELLS Inventor: David P. Majors, Jr., Harvey, La.

Schlumberger Technology Corporation, New York, NY.

Filed: May 9, 1973 Appl. No.: 358,575

Assignee:

I References Cited UNITED STATES PATENTS Primary Examiner-James A. Leppink Attorney, Agent, or FirmDavid L. Moseley; Stewart .F. Moore; William R. Sherman [451 Apr. 9, 1974 57} ABSTRACT In accordance with an illustrative embodiment of the invention disclosed herein, an apparatus for releasably latching the lower end of a tubing string in a well casing having alanding nipple therein includes laterally flexible anchors carried by a body structure and held inwardly during running. When the anchors encounter the recesses in the nipple, they resile outwardly to stop downward movement, whereupon a clutch can be released to enable the body structure to be moved downwardly to releasably lock the anchors in set position. A seal on the body structure closes the tubing-tocasing annulus so that it can be used for a pressure path to a remote controlled safety valve installed in the tubing above the latching apparatus. The anchors and body structure are provided with coengageable axial cam surfaces that are automatically engaged by downward movement and releasable by relative rotation so that the latching apparatus can be repeatedly set and released as required during installation of the surface equipment.

8 ch fiillfil l l t Fi ur PATENTED APR 9 I974 FIG] I l. TIGERS sum 1 or z FIG. 2B

LATCHING APPARATUS FOR INSTALLING SAFETY VALVES OR THE LIKE IN WELLS This invention relates generally to downhole safety valve installations, and more particularly to a new and improved repeatable latching assembly for anchoring the lower end of a production tubing having a remote controlled safety valve therein in a well casing.

Remote controlled safety valves are commonly used in producing wells as a means of providing downhole protection against disastrous surface fires and blowouts caused by failure, leakage or loss of surface equipment such as valves and flow lines. This type of safety valve is usually spring loaded to be normally closed, but is held open bythe pressure of fluid in a control line extending to the surface. An absence of control pressure in the line due to the sensing of actual or impending surface disaster enables the valve to automatically close and shut-in the well downhole.

' The remote controlled type of safety valve, while being preferred by many well owners, normally requires the existence of a special landing sub in the production string. The sub has spaced apart seal surfaces with a lateral port therebetween that is coupled to the control line extending externally of the production string in order to feed pressure to the valve which is installed inside the sub. Where such equipment has not been previously installed as a part of the well casing program, it becomes quite expensive to make such an installation. Moreover, in the so-called tubingless" completion wells, were a small diameter casing is cemented in the borehole and serves as the production string, it may not be possible to install the landing sub and control line necessary for convention remote control valve installation. However, it has been typical practice to install in most wells at least a landing nipple that will accept a so-called velocity sensitive safety valve. This type of valve, does not require a separate control line, but is spring loaded to be normally open and incorporates a flow restriction that creates a pressure drop, with the resultant force overcoming the spring at a predetermined excessive flow rate and causing the valve to close. Of course this-type of landing nipple is'not normally considered to be compatable with a remote controlled safety valve installation.

It should also be noted that the need for a separate control. line itself has made the installation of remote controlled safety valve quite expensive compared to other type valves, since the lines must be'run with the tubing. This requires a considerable amount of additional rig time and handling expense.

lt is therefore one object of the present invention to provide a new and improved apparatus that enables a remote controlled safety valve to be installed in an existing well that has a typical landing nipple capable normally of accepting only a velocity sensitive-type safety valve.

Another object of the present invention is to provide a new andimproved apparatus that enables the installation of a remote controlled safety valve in an existing well and in such a manner as to eliminate the requirement for a separate control line extending to the top of the well.

It is highly desirable in the design of a structure of thistype that it be repeatable in operaton, that is to say that the structure possess the capability to be set and released with respect to the landing nipple as many times as may be required to facilitate installation of surface flow control equipment. The production string of tubing that extends to the surface may be put in tension or compression, and it then becomes necessary to make a precise measurement for purposes of cutting off the tubing at a required point for setting hangers or the like in the casing head. Thus a latching apparatus for the lower end of the tubing will be set to enable such measurement and marking, released to enable the pipe to be cut and then set again during final installation of the surface equipment.

Accordingly, still another object of the present invention is to provide a new and improved apparatus for anchoring the lower end of a tubing or other well pipe in a previously installed landing nipple, the apparatus being constructed and arranged in such a manner that it can be repeatedly set and released during installation of surface flow control equipment.

These and other objects are attained in accordance with the concepts of the present invention through the provision of a latching apparatus for attaching the lower end of the production string to a previously installed, conventional, velocity valve landing nipple in such a manner that the tubing-towasing annulus can be used as a pressure path to control the operation of a remote controlled safety valve located in the tubing string thereabove. The apparatus, in a preferred form, comprises a body member or mandrelhaving its upper end adapted for connection to the pipe string, and a friction drag assembly carried by its lower end portion. The drag assembly has friction elements in engagement with the well casing wall, and is movable between a lower position and an upper position with respect to the mandrel. The assembly is releasably coupled to the mandrel in the lower position by a mechanism that can be released in response to rotation of the tubing. An anchor sleeve is fixed to the upper end of the drag assembly and is provided with laterally flexible spring fingers having head portions that normally are held inwardly alongside a reduced diameter section the mandrel as the apparatus is being run into the casing, however when the landing sub is reached the head portions are sized and arranged to shift outwardly into a locking recess in the sub. When this occurs the tubing can be rotated to release the coupling to the drag assembly, and then lowered to cause the head portions" to be engaged by a locking surface on the mandrel Also, the head portions and mandrel have coengageable ratchet-type cam surfaces that automatically engage to lock the mandrel in its lower position where a seal assembly on the upper'end portion thereof engages a surrounding sea] surface on the landing sub to prevent fluid leakage. The cam surfaces are preferably formed on a helix so as to enable releasethere in response to rotation of the tubing. Inasmuch as the total production flow must now pass through the mandrel and into the tubing, a remote controlled safety valve installed in the tubing thereabove can be actuated because the tubing-to-ca'sing annulus located above the seal assembly may be employed as a means to provide control pressure to hold the valve open. Thus the apparatus of this invention enables this' type of valve to be installed in almost any existing well, and eliminates the need to have a separate control line that extends in the annulus to the surface.- Moreover, the provision of locking cam surfaces that are automatically engaged and selectively releasable enables a repetitive operation of the latching apparatus as may be required during installation of surface equipment.

The present invention has other objects and advantages that will become more readily apparent in connection with the following detailed description, taken in conjunction with the appended drawings in which:

FIG. 1 is a schematic representation of a cased well with a production string of tubing anchored therein in accordance with the principles of the present invention.

FIGS. 2A and 2B are longitudinal sectional views of the latching apparatus with the parts in relative position for running into the well; and

FIGS. 3A and 3B are views similar to FIG. 2 except with parts in relative positions when anchored and sealed off with respect to a landing nipple installed in the casing.

Referring initially to FIG. 1, a downhole safety valve installation is shown somewhat schematically as including a string of production tubing located concentrically within a well casing 11. The well casing 11 has a landing nipple 12 disposed therein, and the latching assembly 13 in accordance with the concepts of the present invention is shown locked into the landing nipple. As will be described in greater detail herebelow, the latching assembly 13 includes a hollow mandrel 14 that carries anchors 15 to lock the assembly in place within the landing nipple 12, and seal packing 16 that prevents fluid leakage between the mandrel and the casing to confine the total flow of production fluids to the bore of the mandrel. A friction drag mechanism 17 together with a clutch l8 cooperates in enabling setting and releaseof the anchors 15 in response to appropriate manipulation of the mandrel 14 by the tubing string 10.

The production string 10 can have a landing nipple 20 positioned therein and adapted to receive a wireline settable and retrievable, remote controlled safety valve as will be familiar to those skilled in the art. As previously mentioned, this type of landing nipple has a port 21 located between upper and lower internal seal surfaces via which control pressure is communicated to the valve. For further detail of this type of landing nipple and safety valve, reference may be had to p. 3501 of the l972l973 edition of the Composite Catalog of Oilfield Equipment and Services. Alternatively, a typically constructed remote controlled subsurface'safety valve can be joined in the tubing above the latching assembly 13, and would have a pressure port in direct communication with the annulus space between the tubing and the casing so that the valve can be maintained in the open position by fluid pressure applied to the annulus. In either case, moreover, the sub or the valve may be connected to the upper end of the mandrel 14 by a joint of tubing 22 or the like. In the event of surface disaster where the applied pressure is lost or dissipated, the valve is designed in a conventional manner to automatically close and shut-in the well.

Turning now to FIGS. 2A and 2B for structural details of the latching assembly 13, the mandrel 14 can be connected by threads 25 to the lower end of the section of tubing 22 and has an outwardly directed shoulder 26 above which is disposed the annular seal assembly 16. The seal assembly 16, which can take any suitable form, is shown as including chevron packing elements 27 and 28 together with appropriate spacer rings 29-31. The upper end of the seal assembly 16 may be retained by the lower end face 32 of the tubing section 22. When positioned within the landing nipple 12, the seal assembly 16 engages a surrounding seal surface so that the total flow of production fluids is constrained to pass through the central bore 33 of the mandrel 14. The lower end of the mandrel 14 is connected by threads 34 to a bottom sub 35 (FIG. 28) through which the production fluids enter.

The friction drag assembly 17 is carried intermediate the ends of the mandrel 14 and includes a plurality of circumferentially spaced bow springs 38 or the like that extend outwardly into frictional engagement with the inner wall surface of the casing 11 to prevent relative rotation. The ends of the bow springs 38 are retained by caps 39 and 40 that are located near the respective ends of an annular cage 41 and fixed with respect thereto by threads 42 or the like. The caps are, of course, arranged to provide for a certain amount of vertical movement'of the ends of the bow springs to accommodate lateral flexure thereof. The cage 41 has a counterbore 43 that provides an upwardly facing stop surface 44 that is aligned for engagement by an outwardly directed shoulder 45 on the mandrel 14 to provide a stop limit to upward movement of the drag assembly with respect to the mandrel. However, as the device is being run into the well, the drag assembly 17 is held in a lower position with respect to the mandrel 14 by the clutch 18 that includes flexible fingers 46 depending from the lower cap 40 and having upwardly facing teeth 47 to are normally engaged with downwardly facing teeth 48 on the lower sub 35. The teeth 47 and 48 preferably are formed on aright hand helix so that rotation of the mandrel 14 to the right will unthread the sub 35 from the fingers 46 and enable downward movement. Of course the clutch 18 can be reen gaged without rotation by simply moving the mandrel 14 upwardly because the teeth 48 can ratchet back into engagement with teeth 47 due to the capability of the fingers46 to resile outwardly.

An anchor sleeve 50 is threaded at 51 to the upper end of the cage 41 and is longitudinally cut by a plurality of slots 52 all extending from the upper end thereof for less than its full. length inorder to provide a plurality of circumferentially spaced, flexible spring fingers 53. Each spring finger 53 has an enlarged head portion 54 at its upper end and an outwardly directed shoulder 55 intermediate its ends. The head portions 54 each have an upwardly and inwardly inclined upper surface 56 and a transverse lower surface 57, together with internal buttress-type threads 58 that face downwardly and are sized to mesh with external threads 59 on an enlarged section 60 of the mandrel 14 as will be more fully described herebelow. During running, the head portions 54 are located as shown in FIG. 2A adjacent to a reduced diameter portion 61 of the mandrel and are held in an inwardly flexed and inactive position by the shoulder 55 whose outer surfaces 62 are adapted to slide in contact with the inner wall of the casing 11. When the head portions 54 and shoulder 55 arrive at a landing nipple having complementary shaped internal recesses, however, they are permitted to move outwardly relative to the mandrel 14 to a' position where the transverse surfaces 57 stop downward movement. Moreover, when the clutch 18 is released as will be subsequently explained, the enlarged diameter section 60 of the mandrel 14 can be positioned behind the head portions 54 in a manner such that a locking surface 64 will function to prevent inward movement. Due to the capability of the head portions 54 to flex laterally to some extent within the recesses of the landing nipple, it will be recognized that the external teeth 59 can be ratcheted into engagement with the internal teeth 58 in response to only downward movement of the mandrel 14. Moreover, due to the downwardly and inwardly inclined formation of the internal teeth 58, then engagement with with the'teeth 59 serves to lock the mandrel 14 in a lower positon within the landing nipple where the seal assembly 16 engages a surrounding seal surface therein.

In operation, the parts are assembled as shown in the drawings and run into the casing 11 with the threads 47 and 48 on the clutch sleeve 46 and the bottom sub 35, respectively, engaged to position the anchor assembly and the drag assembly 17 in a lower position along the mandrel 14. The shoulder 55 engage in inner wall of the casing 11 as shown in dotted lines in FIG. 2A, causing the fingers 53 to resile inwardly and thereby positioning the head portions 54 alongside the reduced diameter section 61 of the mandrel. When the latching assembly arrives at the seating nipple 12 as shown in FIG. 3A, which contains spaced apart internal recesses 70 and 71 that are companion in shape and spacing to the outline of the head portions 54 and the shoulders 55, the shoulders enter the lower recess 71 and enable the head portions 54 to resile outwardly into the upper recess 70. The shoulder surfaces 57 come into abutting contact with an opposed shoulder surface 72 that defines the lower wall of the upper recess 70. to provide a stop-against downward movement and to locate the seal assembly 16 in contact with the surrounding seal surface 73.

Then the mandrel 14 is rotated by the tubing 10 to the right, resulting in release of the clutch threads 47 and 48 since the cage 41 is held against rotation by the drag springs 38. When the threads 47 and 48 are released, the mandrel 14 can be telescoped downwardly with respect to the anchor sleeve 50 to position the locking surface 63 behind the head portions 54 and prevent their inward movement. The threads 59, preferably of buttress formation with downwardly and outwardly inclined outer surfaces as previously described, ratchet into the companion threads 58 on the head portions 54 to lock the mandrel in the lower position. Any upward force on the mandrel 14 will only result in a more firm anchoring due to a camming action of the inclined surfaces 56 and 74 on the head portions 54 and at the upper end'of the recess 70, respectively. In this condition of parts, the lower end of the tubing 10 is firmly anchored and sealed within the landing nipple 12. Moreover, the annular space 75 between the casing l 1 and the tubing 10 provides a pressure path from the surface to the remote controlled safety valve positioned within the nipple above the latching assembly 13. To release the latching assembly 13, it is only necessary to rotate the mandrel 14 to the right while holding a strain in the tubing. This causes the threads 58 and 59, which are preferably of left hand formation, to disengage and enables the. locking surface 63 to be removed. from behind the head portions 54 as the mandrel 1 4 shifts upwardly. At the limit of its upward relative movement, the clutch 18 will automaticallyengage as the sub teeth 48 ratchet back into engagement with the teeth 48 on the clutch sleeve 46. As the drag assembly 17 and the anchor sleeve 50 are forced upwardly,

the spring fingers 53 are flexed inwardly to.a disarmed position due to camming action of the inclined surfaces 56 and 74, and are held in such position by the shoulders which disengage from the recess 71 and slide along the inner wall of the casing 11. If it is desired to reset the latching apparatus, such can be accomplished by duplicating the procedure outlined above, and for that matter the assembly 13 can be set and released as many times as desired to facilitate spacing procedures at the surface that are sometimes necessary when installing surface production facilities.

It will now be recognized that a new and improved latching assembly has been provided that enables the installation of remotely controlled subsurface safety valve equipment in existing wells. Moreover, the tubing-to-casing annulus can be utilized as a pressure path for control pressure to actuate such valves, eliminating the need for running separate control pressure lines ex-' ternally of the production tubing. The operation of the device is repeatable to facilitate installation of surface equipment. Since certain changes or modifications may tions falling within the true spirit andscope of the present invention.

I'claim:

1. Apparatus for use in anchoring the lower end of a production pipe in a well casing having a landing nipple therein providing internal recess means, comprising: a body member carrying seal means adapted to engage said landing nipple to block fluid flow between said casing and said body member; anchor means comprising laterally flexible members movable relatively along said body member between an inactive position alongside said body member and an anchoring position in engagement with said recess means; clutch means for normally retaining said anchor means in said inactive position and releasable in response to relative rotation to permit movement along said body member to said anchoring position, and releasable lock means on said body member and said anchor means for locking said body member against upward movement with respect to said anchor means when said anchor means are engaged in said recess means, said lock means being automatically engaged by downward movement of said body member without rotation, and released by relative rotation of said body member.

2. The apparatus of claim 1 wherein said lock means includes upwardly and outwardly inclined cam surfaces on said body member cooperable with downwardly and inwardly inclined cam surfaces on said anchor means, said cam surfaces enabling automatic engagement of said lock means during downward relative movement of said body member.

3. The apparatus of claim 2 wherein said cam surfaces are formed by helically arranged thread formations to enable release by body member.

4. The apparatus of claim 3 wherein said thread forsaid relative rotation of said mations are a buttress-type thread of left hand disposaid body member and said anchor means that is releasable in response to right. hand rotation of said body member.

6. Apparatus for use in anchoring a production string or the like in a well casing having internal recess means formed therein, comprising: a body structure having larger and smaller diameter portions; laterally flexible anchoring heads movable longitudinally along said body structure and between an inner position adjacent said smaller diameter portion and an outer position adjacent said larger diameter portion, said heads when in said outer position being received in said recess means; and downwardly and inwardly sloping cam means on are provided by buttress thread tooth formations. 

1. Apparatus for use in anchoring the lower end of a production pipe in a well casing having a landing nipple therein providing internal recess means, comprising: a body member carrying seal means adapted to engage said landing nipple to block fluid flow between said casing and said body member; anchor means comprising laterally flexible members movable relatively along said body member between an inactive position alongside said body member and an anchoring position in engagement with said recess means; clutch means for normally retaining said anchor means in said inactive position and releasable in response to relative rotation to permit movement along said body member to said anchoring position; and releasable lock means on said body member and said anchor means for locking said body member against upward movement with respect to said anchor means when said anchor means are engaged in said recess means, said lock means being automatically engaged by downward movement of said body member without rotation, and released by relative rotation of said body member.
 2. The apparatus of claim 1 wherein said lock means includes upwardly and outwardly inclined cam surfaces on said body member cooperable with downwardly and inwardly inclined cam surfaces on said anchor means, said cam surfaces enabling automatic engagement of said lock means during downward relative movement of said body member.
 3. The apparatus of claim 2 wherein said cam surfaces are formed by helically arranged thread formations to enable release by said relative rotation of said body member.
 4. The apparatus of claim 3 wherein said thread formations are a buttress-type thread of left hand disposition to enable release and upward movement of said body member in response to right hand rotation thereof.
 5. The apparatus of claim 1 wherein said clutch means is provided by a threaded interconnection between said body member and said anchor means that is releasable in response to right hand rotation of said body member.
 6. Apparatus for use in anchoring a production string or the like in a well casing having internal recess means formed therein, comprising: a body structure having larger and smaller diameter portions; laterally flexible anchoring heads movable longitudinally along said body structure and between an inner position adjacent said smaller diameter portion and an outer position adjacent said larger diameter portion, said heads when in said outer position being received in said recess means; and downwardly and inwardly sloping cam means on said heads engageable with upwardly and outward sloping cam means on said larger diameter portion to enable downward movement of said body structure relative to said heads to automatically engage said cam means and lock said body structure against upward movement.
 7. The apparatus of claim 6 wherein said cam means are formed on companion helices to enable release of said cam means by relative rotation.
 8. The apparatus of claim 7 wherein said cam means are provided by buttress thread tooth formations. 